The present invention relates to power delivery devices, and more particularly to a power supply that delivers controlled electrical signals for use in electrochemical processes, including material deposition and removal.
Various processes for depositing and removing material, i.e., plating and etching, are known. For example, chemical plating involves plating via chemical reaction. In this type of chemically mediated process, the plating is controlled via control of the chemical reaction during the plating process. While this process tends to provide a robust plating, it also provides a lesser degree of control over the plating process. Furthermore, EPA regulations make this type of processing more costly and complex because the purely chemically mediated plating process requires controlling large quantities of EPA-regulated chemicals.
Electrical plating, or electrolytic plating, involves providing a potential across the object to be plated while the object is in contact with the plating material. This can be done, for example, by submersing the object within a bath of plating material. The plating material builds up upon the object due to the electrical potential at the outer surface of the object. However, because a greater build-up of electrical charge occurs at these locations, the plating tends to build up around edges and sharp protrusions in this type of process. The more irregularly shaped the object, the more difficult it is to apply a uniform layer of plating. Furthermore, the effective depth of the plating on the object is also limited by this process. While this type of process tends to be more controllable than chemical plating processes, it is still somewhat limited by complex geometry of the object that is difficult to reach during processing.
Due to the drawbacks of the aforementioned plating processes, electrochemical plating has gained increased acceptance. This process combines the benefits of controllability of electrolytic plating and the quality of chemical plating. Electrochemical processing includes electroplating, deposition by electrochemical means, electromachining, etching by electrochemical means and anodizing. Since the process also relies on electrolytic plating, lesser quantities of chemicals are required to effectuate the plating process. However, control of the electrical characteristics of the plating process has become increasingly important.
Control of the electrochemical plating process can be achieved through control of the power supply signal to the plating electrodes. Due to increasing complexity of objects requiring plating, particularly in the micro-electronics industry, the need for power supplies allowing for precise control over the signals produced has grown. Signals that produce pulses having varying positive and negative magnitudes are needed to gradually build up metal layers on surfaces, and to remove excess build-up in problematic areas are a necessity. Furthermore, more precise control and optimization of the electrical signal can help overcome limitations of specific process conditions including, but not limited to chemistries between two or more substances, current, voltage, power, and impedance.
Therefore, there is a need for a power supply device that optimizes the resulting plating of an object during the electrochemical plating process while also offering precise control of the plating process through control of electrical signals produced by the power supply.
The present invention is directed to a power supply device, particularly for supplying a controlled electrical signal in an electrochemical process. One embodiment of the present invention is a power delivery device providing an electrical signal in an electrochemical process involving an object. The power delivery device comprises a power stage having an input for receiving a power signal and an output being operably connected to the object. A sensor is operably connected to the output. A controller is operably connected to the output and responsive to the sensor. A modulator is operably connected between the controller and the power stage wherein the power stage outputs the electrical signal to the object in response to the modulator and the controller.
Another aspect of the present invention is directed to a power delivery device for providing an electrical signal for an electrochemical process wherein an object is operably connected to the power delivery device. The power delivery device comprises a tracking power stage being operably connected to the object. An output power stage provides the electrical signal to the object. The output power stage is operably responsive to the tracking power stage wherein a dynamic power dissipated by the output power stage is minimized.
In another aspect of the invention, a power supply device is provided that generates a controlled AC xe2x80x9cripplexe2x80x9d content on a DC signal for the purpose of electrochemical processing.
In another aspect of the invention, a device is provided that modulates and controls the power signal in a constant power mode or a dynamic power mode, in addition to constant voltage/constant current mode, for the purpose of electrochemical processing.
In yet another aspect of the present invention, a device is provided that utilizes one or more digital signal processors (DSP) for the purpose of controlling and/or modulating an electrical signal based on a feedback signal from one or more sensors of a plating or etching apparatus for the purpose of real-time operation, e.g., control, of an electrochemical processing.
Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.